1. Field of the Invention
The present invention relates to novel platinum complexes which show potent antibacterial and/or antitumor activities with low toxicity.
2. Prior Art
Compounds analogous to cisplatin [Bristol Myers Co.] and their mechanism of pharmacological action have been investigated since antitumor activity of cisplatin was observed. In fact many platinum complexes such as malonato(1,2-diaminocyclohexane)-platinum(II) [U.S. Pat. No. 4,169,846], cis-dichloro-transdihydroxy-bis(isopropylamine)platinum(IV) [U.S. Pat. No. 4,394,319], and the like are known presently.
The present inventors have investigated to develop platinum complexes analogous to cisplatin from the early stage of study and prepared novel platinum complexes described in European Pat. No. 0057023, British Pat. Pub. Nos. 2132201A, 2140804A, JPN Unexamd. Pat. Pub. No. 59-222497, and the like.
Problems in the prior art will be illustratively explained. Cisplatin has the following problems.
(i) It can not be administered easily because of its low water- and fat- solubility, whereby its utility is limited.
(ii) Toxicity, particularly nephrotoxicity is high.
The present inventors have studied to improve the solubility of the compounds of the present invention in order that the compounds can be administered easily. They also have studied to reduce the toxicity and increase the activities.
As the result of the studies, they have succeeded in preparing novel platinum(IV) complexes which have a bidentate ligand of the formula: ##STR1## (wherein R is hydrogen, phenyl, or optionally substituted lower alkyl), N-base donors as monodentate ligands (e.g., amine, primary amine) or bidentate ligand such as a diamine, and two monodentate ligands.
The alphabets a.about.f are utilized for indicating the relative configuration of each ligand in three dimensions. ##STR2##